In my forward curb side air conditioning compartment is a 12v relay system. I found it clicking on and off today. I think it might have failed and have no idea what it controls. I pulled a wire jumper between the red relay and the silver one, and the clicking stopped. Picture attached. Any ideas?
Alarm system and/or electric step stuff. So said Newell on my walk around many years ago.
There is an automotive fuse that when removed caused the steps to raise. With the jumper removed from red relay to silver relay steps seems to operate normally. There is a bay light right underneath the relay, and most of the time when I flip the switch to the light I get the red relay clicking, but no light. I only measure about 6v on the light which maybe why no light.
If the power supply to the red relay also powers the light then there is resistance in the supply circuit before it splits to supply the two devices. I'm thinking that the coil in the red relay holds ok until some new load is added to the circuit which drops the voltage. When the coil drops out, the total load decreases so the voltage rises to the point the coil pulls in again. Something like this is happening because every time you do something that reduces electric consumption the red relay stops clicking.
Jon, thanks for the explanation. So what is the fix? Or next step troubleshooting? Do I need to replace the red relay?
Mike: the way I would proceed (which is imaginary since it really helps me to see how things are arranged) is to find the power supply wire and check the voltage on it with and without the light on. This attempts to determine if the spot of resistance is before or after the connection to the relay. You will want to measure the voltage on both the female and male parts of the connection as this tell you if the connection itself might be the bad spot. If the incoming drops voltage when the light is on, then I would head to the fuse supplying this circuit and check the voltage on each side of the fuse, I've had fuse holders build up resistance.
In any case, what you do from the first step of checking the voltage at the input to the relay is work your way from that spot outwards in the circuitry until you run across an unexpected voltage drop. It could be in the relay (unlikely in my opinion) or in a wiring connection (most likely)
Let us know what you find and we can help from there. It would also help to draw a wiring schematic of the system as you work on it. With wires seemingly going everywhere I find it hard to keep track of it all and know where I'm at so I tend to draw diagrams as I go. The "black boxes" of the relays make it difficult to follow the circuits through them, but with a little persistence it can be sussed out. The more we know about how the system is put together the easier it is to troubleshoot.